Report CI failures to Matrix channel

[jobara]

Is your feature request related to a problem? Please describe.

For GitHub actions that aren't part of a PR it can be opaque when there is a failure. You have to look for the action to see if it failed.

Describe the solution you'd like

For actions that aren't part of PR, it would be helpful to ping the Matrix channel with the related failure.

Describe alternatives you've considered

No response

Additional context

This issue came up related to #2569

[jobara]

Can look at using https://github.com/matrix-org/matrix-js-sdk to make the calls, but would require setting up a matrix user account to send the messages from.